Killie looked like claiming a valuable point in their bid to beat the drop before a 15-minute second-half blitz sent them spinning to their eighth defeat in nine matches in all competitions.
Calderwood was left to rue the schoolboy defending that handed Accies what he and opposite number Billy Reid agreed was a flattering victory.
Calderwood said: "In the end, it looks like a battering but it definitely wasn't a 3-0.
"That's the way we are at the moment away from home."
He added: "I was well pleased with our performance in the first half.
"I thought we were the better team without creating too many chances - again."
Killie, who slipped to second bottom of the SPL table, went into today's game having scored just four league goals away from home all season.
"We had a couple of chances on the counter-attack but we've not got a cutting edge away from home," said Calderwood.
"It's cost us all season. I just said it to them.
"As soon as you go behind and the heads are down, it makes it very difficult for you."
Dougie Imrie handed Hamilton a 72nd-minute lead with his first goal for the club, before a sweet strike from Flavio Paixao and fine finish from Joel Thomas wrapped up the win.
Calderwood was critical of the defending for all three goals, adding: "It's kids' stuff."
But he insisted he had seen enough to convince him Killie could survive.
"Our first-half performance was probably one of the best performances since I've been here, without creating too much," he said.
"They were physical, (Liam) Kelly and (Craig) Bryson in midfield did really well, the two boys up front worked their socks off.
"I think if we'd have got the first goal, we'd have won the game.
"That's how tight it was and it looks as if we've been hammered again."
The result guaranteed a third straight season of SPL football for Hamilton but boss Billy Reid shrugged off the significance of the outcome.
"I've been fine all season because I did say I thought it was a smashing group of players I had," he said.
"I thought we had to earn the right to win that football match today.
"Kilmarnock were very competitive; I thought they matched us in every department in the first half.
"We went to Kilmarnock a few weeks ago and we beat them 2-1 and I thought we were convincing winners on that day.
"I thought 3-0 was a wee bit harsh on Kilmarnock today if I'm being honest.
"If they continue to work as hard as that then they'll be fine."